Abstract
We propose a model of baryogenesis achieved by the annihilation of non-thermally produced WIMPs from decay of heavy particles, which can result in low reheating temperature. Dark matter (DM) can be produced non-thermally during a reheating period created by the decay of long-lived heavy particle, and subsequently re-annihilate to lighter particles even after the thermal freeze-out. The re-annihilation of DM provides the observed baryon asymmetry as well as the correct relic density of DM. We investigate how washout effects can affect the generation of the baryon asymmetry and study a model suppressing them. In this scenario, we find that DM can be heavy enough and its annihilation cross section can also be larger than that adopted in the usual thermal WIMP baryogenesis.
Highlights
The baryon density at present inferred from Cosmic Microwave Background (CMB) anisotropy and Big Bang Nucleosynthesis (BBN) is [1]ΩBh2 = 0.0223 ± 0.0002, (1)which corresponds to the baryon asymmetry YB ≡ nB s ≃ 0.86 × 10−10, (2)where nB and s is the baryon number density and entropy density respectively
Note that dark matter (DM) are in the thermal equilibrium initially and frozen and soon become dominated by the non-thermal components produced from the decay of φ at around a/ai ≃ 103 corresponding to x = mχ/T ≃ 20
We have proposed a weakly interacting massive particle (WIMP) baryogenesis that can be reconciled with low reheating temperature
Summary
The baryon density at present inferred from Cosmic Microwave Background (CMB) anisotropy and Big Bang Nucleosynthesis (BBN) is [1]. Baryogenesis is successfully achieved because the WIMP annihilations violate baryon number, C and CP, and the out-of-equilibrium is attained when the DM number density is deviated from the thermal equilibrium For this scenario to be effective, the temperature of the Universe must be larger than the freeze-out temperature of DM which is Tfr ≃ mχ/20. In the models with such a long-lived particle, the reheating temperature can be low enough With such a low-reheating temperature, the relic abundance of DM can not be explained in simple models for thermal WIMP freeze-out. It is questionable whether baryon asymmetry can be successfully generated in models with low-reheating temperature.
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